Model for remaining strength estimation of a corroded pipeline with interacting defects for oil and gas operations

Abstract

Remaining strength estimation of corroded pipelines is a major consideration in pipeline integrity management. The loss of pipe wall thickness due to corrosion inevitably leads to a reduction in the pipeline’s strength and ability to sustain a design pressure. If corrosion defects are closely spaced, the corrosion feature may interact, resulting in failure pressure lower than would be expected if the defects were evaluated as separate flaws. In such a situation, industry methods for remaining strength calculation have been shown to be conservative. This present work presents a new model that improves the current methodologies for estimating the remaining strength of a corroded pipeline with interacting defects, utilizing a finite element analysis approach in combination with curve fitting. The new model demonstrates the potentials of improved estimation of the remaining strength over the existing industry models. The implication is that the presented model has the potentials of reducing the conservatism inherent in the existing models for estimating the remaining strength of oil and gas pipelines.

Keywords

• remaining strength estimation
• corroded pipelines
• pipeline integrity management
• finite element analysis
• interacting defects
• oil and gas